The invention concerns a method for producing small, sheet glass plates having a specified geometric structure and lateral expansions in the millimeter range by removing them from a larger sheet glass plate.
The invention further concerns such a larger sheet glass plate having dimensions in the centimeter range as a semifinished product for producing the small, sheet glass plates having lateral expansions in the millimeter range.
Small, sheet glass plates of the aforementioned type are needed in certain technical fields, in particular for the production of electronic components.
For example, small containers, among other things, that are closed completely or partially on at least one side by a sheet glass plate are used to house micro-and optoelectronic components such as vibrating quartz crystals, SAW filters, CCD components, the “electronic packaging”. Housing covers made of sheet glass are also used frequently in the housing of micro-and optoelectronic components. The thickness s of these small sheet glass plates is typically in the range of 10 μm≦s≦500 μm. Sheet glass plates having the most diverse geometry (rectangular, circular, etc.) are used in this application. The edge length and/or diameter of such plates made of sheet glass typically measure only a few millimeters in size.
Small sheet glass plates are also used as structural components in the production of microelectronic and micromechanical components. It is made known in DE 196 49 332, for example, that a vibrating quartz crystal is positioned directly between two sheet glass plates and interconnected with them. Bonded structures of this type have a minimal height and are capable of being placed and contacted on a printed-circuit board or a base plate.
In this application of sheet glass as an element for closing a housing for micro-and optoelectronic components, as well as a structural element of microelectronic or micromechanical components, the bond is typically formed by means of adhesive bonding or soldering. In the case of soldering, metal or glass solder is used as the joining material. Glass solder is used in the majority of applications.
The production of small, sheet glass plates of this type is typically carried out according to the related art (Derwent abstract of JP 62-070241) by removing them from larger sheet glass plates. The separating procedure is carried out by means of abrasive cutting or boring using rotating diamond tools. At the same time, higher requirements are placed on the quality of the edges, since they have a decisive influence on the strength of the sheet glass plate.
The sheet glass plates are typically divided initially in the manner described previously and then subjected to the subsequent further processing steps (assembly and joining process). In the case of the joining technique currently used in many housing applications, the sheet glass plates are bonded with the housing by means of a soldering process. In the majority of applications, the soldering material is applied to the glass using a dispenser. The soldering material is typically applied in the edge region of the sheet glass plates and therefore usually forms a thin, closed, frame-shaped contour. Glass or metal solder is typically used. Another method of applying the soldering material to the joining zone that is also used to a certain extent in common practice is the use of presintered solder frames. In this application, the sheet glass plates and a free and likewise very thin, presintered solder frame made of glass solder must be positioned and partially fixed in position relative to each other and relative to the housing with which the sheet glass plates are to be bonded.
In the case of this further processing method, problems occur with handling and positioning due to the minimal lateral expansion, thickness and mass of the sheet glass plates, as well as the solder frame used. This handling problem occurs to a greater extent, in particular, when thin, free solder frames are used. On the one hand, the thin glass plates are comparably susceptible to breakage and, on the other, the ratio of gravitational force to the adhesive forces occuring during handling is low. In particular, lifting the individual sheet glass plates and the solder frame in defined fashion is difficult, so that the individual components must be handled manually in the majority of cases. This manual handling is time-consuming and personnel-intensive, which makes it cost-intensive. Moreover, waste due to breakage and contamination increases when this type of handling is used and during transport of the individual sheet glass plates.